Phenomenology of Stabilizing Moduli in a Framework of G2 Compactification of M-Theory.

Abstract

This thesis explores an interesting class of fluxless G2 compactifications of M-theory, where all the moduli are stabilized and a TeV scale is generated with the Planck scale as the only dimensionful input. A well-motivated phenomenological model -- the G2-MSSM, can be naturally defined within this framework. In this thesis, important phenomenological aspects of the G2-MSSM are carefully studied. First, the soft supersymmetry breaking parameters and the superpartner mass spectrum are computed. The spectrum is found to contain light gauginos and heavy scalars with a wino LSP when the vacuum energy is tuned to be small. The prospects for discovery at the Large Hadron Collider~(LHC) are promising. The model predicts a spectacular four-top signature, which can be easily identified at the LHC. In addition, the charginos are meta-stable and could be detected directly at the LHC providing additional information about the nature of the LSP. Second, in the G2-MSSM CP-violating phases occur in the quark and lepton Yukawas but are not generated from the supersymmetry breaking. However, in such models additional CP violation can be generated because the soft trilinear matrices are not proportional to the Yukawa matrices. The estimated upper bounds for the electric dipole moments of the electron, neutron and mercury are all within the current experimental limits and could be probed in the near future. Finally, the cosmological moduli/gravitino problems and the issue of too little thermal but excessive non-thermal dark matter from the decays of moduli are studied. It is shown that the late decaying moduli not only satisfy the Big Bang Nucleosynthesis constraints but also avoid the gravitino problem. The non-thermal production of wino LSPs gives a right amount of relic density. The phenomenological results obtained in this thesis can be tested by coming experiments, particularly the LHC experiments, and therefore provide a means to connect the experimental data to a high scale theory. The results will also be useful in helping recognize the signal of this framework experimentally and allow us to further distinguish it from other competing theories.